This invention relates to a call and connection separated telecom network, wherein software related to service handling is separated from software related to connection handling. In particular service handling takes place at a call layer while connection handling takes place at a connection layer. In the following a call and connection separated telecom network is referred to as a CCS network.
A connection which goes from the CCS network to an external network and from there back to the CCS network and which uses a service that is administered completely within the CCS network is called an inhomogeneous connection. In an inhomogeneous connection all service handling takes place within the CCS network, while connection handling takes place in the CCS network as well as in the external network.
A call the service and connection handling of which takes place solely within the CCS network is said to be carried by a homogeneous connection.
Service handling includes service control, service execution, service signalling, service installation, service modification and service administration.
Connection handling related to the set up and release of connections and to the control of the physical telecom network which comprises switches, trunks extending between switches and other hardware devices, such as tone senders, conference equipment, connected to the switches.
The connection layer is an abstraction that comprises a model of the physical network, its switches and its trunk lines. Subscriber data, routing tables and information of general character relating to a group of switches, to the trunk lines extending between said group of switches and to the subscribers and subscriber lines served by said group of switches are stored in a common data base. Said group of switches, trunk lines, subscribers and subscriber lines are in the following referred to as a domain. Accordingly a domain has its own database integrity.
Today""s telecommunication networks are characterized by specialization. The telex network transports telex information, POTS (plain old telephony service) is transported by the public switch telephone network (PSTN) package switched data networks (PSDN) based on X.25 protocols transport computer data and coaxial tree network of the community antenna TV network (CATV) transports television signals. Each of these networks is designed for its individual service and can generally not transport another service. For instance PSTN does not transport TV-signals and voice is difficult to transport over an X.25 network because of large end-to-end delay. Only in exceptional cases service transported by one network can be transported by another. For example PSTN, originally designed to transport voice, is capable of transporting computer data at a limited speed provided modems are used at both ends of the network.
It is expensive to build new physical telecom networks for every new service.
U.S. Pat. No. 5,434,852 relates to a communications network for delivery of broadband and narrowband communications services. The communications network has a layered architecture comprising: (a) call servers providing user-to-user and user-to-network functions, (b) service-specific servers providing the services to be used in a call, and (c) connection servers providing for connection establishment and release. Homogeneous connections extending between several networks, all designed in the same manner, are described in the patent.
In U.S. Pat. No. 5,402,471 a method of transferring a connection between PSTN and a mobile telephony network is shown, wherein call control and connection control are separated in predefined intelligence points (mobile switch centers in the mobile telephony network, or exchanges in PSTN). Inhomogeneous connections between the two networks are contemplated. Inhomogeneous connections using an intermediate network are not described therein. For example a call between two mobile stations using the PSTN as an intermediate network is not contemplated, since such a call is routed within the mobile network only. Nor is a call between two subscribers within the PSTN, said call using the mobile network as an intermediate network, contemplated, since such a call is routed within the PSTN only.
A main object of the present invention is to provide for re-use of the physical structure of today""s existing telecommunication networks to transport other services than those for which they were originally designed.
Another object of the invention is to provide a call and connection separated telecom network that allows for establishment of inhomogeneous connections.
Still another object of the invention is to provide a CCS network that uses an external network to set up a connection between two nodes within the CCS network.
A further object of the invention is to provide for re-use of a call originating network access process and of a call terminating network access process for the set up of a homogeneous as well as of an inhomogeneous connection.
Another object of the present invention is to provide a call and connection separated telecommunication network in which a service related signalling is independent of signalling used for set up of connection in such a manner that today""s existing non-separated telecommunication networks are used solely for set-up and control of connections while service related signalling takes place over the signalling network.
The advantages with the invention is that existing networks are used as a medium for setting up connections while the services, existing services as well as future services, are handled by a signalling network generally independent of the physical network used for connection establishment.
The use of a CCS network makes it possible to use the call layer for a particular service and to use the connection layer to set up a connection with the required characteristics, such as STM, ATM, between any two users.
An inhomogeneous connection allows for the use of an existing network to set up a connection, while the service is transported at the call level of the call.
The hardware as well as software of the signalling network constitutes a signalling layer that is generally independent of the hardware as well as software of the connection layer. When new services are created, or existing services are upgraded or modified, this is done solely at signalling layer and is generally independent of the software and hardware used for connection establishment. Some minor modifications only need to be made at the connection layer in order to adapt the connection layer to the new service.
The inventive method is not obligable to existing networks only but be used in connection with new networks as well.
The above objections are achieved by a CCS network as defined by the accompanying claims.